Re: [Alacrityvm-devel] [PATCH v2 2/4] KVM: introduce "xinterface"API for external interaction with guests

[Amit Shah]

On (Tue) Oct 06 2009 [11:18:59], Ira W. Snyder wrote:
> 
> The limitation I have is that memory made available from the host system
> (PCI card) as PCI BAR1 must not be migrated around in memory. I can only
> change the address decoding to hit a specific physical address. AFAIK,
> this means it cannot be userspace memory (since the underlying physical
> page could change, or it could be in swap), and must be allocated with
> something like __get_free_pages() or dma_alloc_coherent().

If the dma area is just one page in size, that page can be pinned by the
host (via a hypercall by the guest). If it's more, there is a
reserve-ram patch by Andrea. That'll reserve some RAM area for the guest
that's 1-1 mapped in the host address space. There was a patch posted on
the list sometime back.

		Amit
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